After several years of trying, members of the Doom community have succeeded in getting the source code to Heretic and its sequel, Hexen to be re-released as free software under the GNU General Public License.

The OpenDocument format (ODF) is a format for electronic office documents, such as spreadsheets, charts, presentations and word-processing documents. The OpenDocument format is supported by free software applications such as OpenOffice.org, AbiWord and KOffice.

There are many services that will host your project's source code, mailing lists and bug trackers. While very few of these services charge for their services, most of them are built on proprietary software. Worse, some of them have started adding adverts for proprietary software in their mailing lists, or refusing projects with certain free software licenses.